5-hydroxytryptamine syndrome is a relatively rare type of neurological syndrome, which is mainly caused by taking 5-hydroxytryptamine drugs, or combining 5-hydroxytryptamine drugs and monoamine oxidase inhibitors. The main clinical symptoms include mental behavioral changes, abnormal motor system function, and autonomic dysfunction, as follows: 1. Mental behavioral changes, patients tend to have psychiatric symptoms, manifested as confusion, unclear content of consciousness, often qualitative orientation disorders of time, place, and people, etc., and manifested as mild mania, excitement, a certain degree of aggression, and easily provoked; 2. Motor system function abnormalities, mainly manifested in muscle activity, limb stiffness, muscle tonus, some patients will have localized limb tremor or muscle clonus, and severe patients will also have ataxia; 3, symptoms of autonomic nervous system dysfunction, mainly manifested in nausea, vomiting, or abdominal pain, diarrhea, and some patients will have obvious nerve excitation resulting in headache, trembling, and sometimes flushing, sweating, and rapid heartbeat. Measurement of blood pressure will be found to be elevated, the measurement of vital signs have obvious shortness of breath, some patients will also have dilated pupils.